U.S. patent application number 15/327156 was filed with the patent office on 2017-09-07 for determining measurement gap patterns.
The applicant listed for this patent is Nokia Solutions and Networks Oy. Invention is credited to Tero Henttonen, Timo Erkki Lunttila, Benoist Pierre Sebire.
Application Number | 20170257785 15/327156 |
Document ID | / |
Family ID | 51301287 |
Filed Date | 2017-09-07 |
United States Patent
Application |
20170257785 |
Kind Code |
A1 |
Henttonen; Tero ; et
al. |
September 7, 2017 |
Determining Measurement Gap Patterns
Abstract
Determining measurement gap patterns A terminal device acquires
(200), from a network node, a message indicating a discovery
reference signal DRS measurement timing configuration for the
terminal device for measuring discovery reference signals, and at
least one measurement gap pattern MGP. The terminal device
determines (206) an effective measurement gap pattern EMGP based on
the at least one measurement gap pattern MGP and the DRS
measurement timing configuration. (FIG. 2)
Inventors: |
Henttonen; Tero; (Espoo,
FI) ; Lunttila; Timo Erkki; (Espoo, FI) ;
Sebire; Benoist Pierre; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nokia Solutions and Networks Oy |
Espoo |
|
FI |
|
|
Family ID: |
51301287 |
Appl. No.: |
15/327156 |
Filed: |
August 8, 2014 |
PCT Filed: |
August 8, 2014 |
PCT NO: |
PCT/EP2014/067054 |
371 Date: |
January 18, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0048 20130101;
H04W 24/10 20130101; H04W 72/0413 20130101; H04W 72/042 20130101;
H04W 16/32 20130101; H04W 76/28 20180201; H04W 56/00 20130101 |
International
Class: |
H04W 24/10 20060101
H04W024/10; H04W 72/04 20060101 H04W072/04; H04L 5/00 20060101
H04L005/00 |
Claims
1-19. (canceled)
20. A method comprising: acquiring, in a terminal device of a
cellular communication system, a control message from a network
node, the control message comprising at least one information
element indicating at least one discovery reference signal (DRS)
measurement timing configuration for the terminal device for
measuring discovery reference signals and at least one measurement
gap pattern; determining, in the terminal device, an effective
measurement gap pattern based on the at least one measurement gap
pattern and the at least one DRS measurement timing
configuration.
21. The method of claim 20, further comprising in the terminal
device: determining whether there are measurement gaps that are not
used for DRS measurements or other measurements, and, if there are,
using those measurement gaps for one or more of PDCCH monitoring,
PUCCH transmission, PUSCH transmission, and PDSCH reception.
22. The method of claim 20, further comprising in the terminal
device: at time instances defined in the effective measurement gap
pattern, performing at least one of intra- and inter-frequency
measurements.
23. The method of claim 20, comprising in the terminal device:
determining carrier-specific effective measurement gap patterns
based on the measurement gaps and the DRS measurement timing
configuration such that only those measurement gaps that coincide
with the DRS measurement timing configuration of the carrier are
included into the carrier-specific effective measurement gap
patterns.
24. The method of claim 23, further comprising in the terminal
device: based on the carrier-specific effective measurement gap
patterns, determining a combined effective measurement gap pattern
indicating which measurement gaps are used in any of measured
carriers.
25. The method of claim 20, further comprising in the terminal
device: monitoring its serving cell during measurement gaps that
are not used for DRS measurements or other measurements.
26. The method of claim 20, comprising in the terminal device:
determining the effective measurement gap pattern based on the
measurement gap pattern and an explicit indication of a DRS
occasion transmission configuration.
27. A method comprising: determining, in a network node, at least
one measurement gap pattern for a terminal device of a cellular
communication system; determining, in the network node for the
terminal device, a DRS measurement timing configuration for
measuring discovery reference signals; causing, in the network
node, transmission of a control message to the terminal device, the
control message comprising at least one information element
indicating an RRC configuration for the terminal device, comprising
the measurement gap pattern and the DRS measurement timing
configuration.
28. The method of claim 27, further comprising in the network node:
determining for the terminal device, an effective measurement gap
pattern, based on the measurement gap pattern and the DRS
measurement timing configuration for measuring discovery reference
signals; and determining whether there are unused measurement gaps
that are usable for normal scheduling of at least one of PUSCH
data, PDSCH data, PDCCH data, and PUCCH data.
29. The method of claim 27, further comprising: configuring cells
with a DRS periodicity other than a measurement gap periodicity of
40 or 80 ms, to obtain effective measurement gaps that coincide
with the DRS periodicity such that DRS timing and the measurement
gap coincide after a fixed number of measurement gap
occurrences.
30. An apparatus comprising: at least one processor; and at least
one memory including a computer program code, wherein the at least
one memory and the computer program code are configured, with the
at least one processor, to cause the apparatus to: acquire, a
control message from a network node, the control message comprising
at least one information element indicating at least one DRS
measurement timing configuration for a terminal device of a
cellular communication system, for measuring discovery reference
signals and at least one measurement gap pattern; determine, an
effective measurement gap pattern based on the at least one
measurement gap pattern and the at least one DRS measurement timing
configuration.
31. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: determine whether there are
measurement gaps that are not used for DRS measurements or other
measurements, and, if there are, use those measurement gaps for one
or more of PDCCH monitoring, PUCCH transmission, PUSCH
transmission, and PDSCH reception.
32. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: at time instances defined in
the effective measurement gap pattern, perform at least one of
intra- and inter-frequency measurements.
33. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: determine carrier-specific
effective measurement gap patterns based on the measurement gaps
and the DRS measurement timing configuration such that only those
measurement gaps that coincide with the DRS measurement timing
configuration of the carrier are included into the carrier-specific
effective measurement gap patterns.
34. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: based on the carrier-specific
effective measurement gap patterns, determine a combined effective
measurement gap pattern indicating which measurement gaps are used
in any of measured carriers.
35. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: monitor its serving cell
during measurement gaps that are not used for DRS measurements or
other measurements.
36. The apparatus of claim 30, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: determine the effective
measurement gap pattern based on the measurement gap pattern and an
explicit indication of a DRS occasion transmission
configuration.
37. An apparatus comprising: at least one processor; and at least
one memory including a computer program code, wherein the at least
one memory and the computer program code are configured, with the
at least one processor, to cause the apparatus to: determine at
least one measurement gap pattern for a terminal device of a
cellular communication system; determine, for the terminal device,
a DRS measurement timing configuration for measuring discovery
reference signals; determine, whether there are unused measurement
gaps that are usable for normal scheduling of at least one of PUSCH
data, PDSCH data, PDCCH, data, and PUCCH data; and cause,
transmission of a control message to the terminal device, the
control message comprising at least one information element
indicating an RRC configuration for the terminal device, comprising
the measurement gap pattern and the DRS measurement timing
configuration.
38. The apparatus of claim 37, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: determine, for the terminal
device, an effective measurement gap pattern, based on the
measurement gap pattern and the DRS measurement timing
configuration for measuring discovery reference signals; and
determine, whether there are unused measurement gaps that are
usable for normal scheduling of at least one of PUSCH data, PDSCH
data, PDCCH data, and PUCCH data.
39. The apparatus of claim 37, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus to: configure cells with a DRS
periodicity other than a measurement gap periodicity of 40 or 80
ms, to obtain effective measurement gaps that coincide with the DRS
periodicity such that DRS timing and the measurement gap coincide
after a fixed number of measurement gap occurrences.
40. A computer program product comprising a computer readable
medium bearing computer program code for acquiring, in a terminal
device of a cellular communication system, a control message from a
network node, the control message comprising at least one
information element indicating at least one discovery reference
signal (DRS) measurement timing configuration for the terminal
device for measuring discovery reference signals and at least one
measurement gap pattern; determining, in the terminal device, an
effective measurement gap pattern based on the at least one
measurement gap pattern and the at least one DRS measurement timing
configuration.
41. A computer program product comprising a computer readable
medium bearing computer program code for determining, in a network
node, at least one measurement gap pattern for a terminal device of
a cellular communication system; determining, in the network node
for the terminal device, a DRS measurement timing configuration for
measuring discovery reference signals; and causing, in the network
node, transmission of a control message to the terminal device, the
control message comprising at least one information element
indicating an RRC configuration for the terminal device, comprising
the measurement gap pattern and the DRS measurement timing
configuration.
Description
TECHNICAL FIELD
[0001] The invention relates to the field of cellular communication
systems and, particularly, determining a measurement gap pattern
for a terminal device.
BACKGROUND
[0002] A communication system may be seen as a facility that
enables communication sessions between two or more nodes such as
fixed or mobile communication devices, access points such as nodes,
base stations, servers, hosts, machine type servers, routers, and
so on. A communication system and compatible communicating devices
typically operate in accordance with a given standard or
specification which sets out what the various entities associated
with the system are permitted to do and how that should be
achieved. For example, the standards, specifications and related
protocols may define the manner how communication devices
communicate with the access points, how various aspects of the
communications are implemented and how the devices and
functionalities thereof are configured.
[0003] An example of cellular communication systems is an
architecture that is being standardized by the 3rd generation
partnership project (3GPP). A recent development in this field is
often referred to as the long-term evolution (LTE) or long-term
evolution advanced (LTE advanced) of the universal mobile
telecommunications system (UMTS) radio-access technology. In LTE,
base stations providing the cells are commonly referred to as
enhanced node-Bs (eNB). eNBs may provide coverage for an entire
cell or similar radio service area.
BRIEF DESCRIPTION
[0004] The invention is defined by the independent claims.
[0005] Embodiments are defined in the dependent claims.
[0006] Although the various aspects, embodiments and features of
the invention are recited independently, it should be appreciated
that all combinations of the various aspects, embodiments and
features of the invention are possible and within the scope of the
present invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the following the invention will be described in greater
detail by means of preferred embodiments with reference to the
attached drawings, in which
[0008] FIG. 1 is illustrates a wireless communication system to
which embodiments of the invention may be applied;
[0009] FIG. 2 illustrates a signalling diagram of a procedure for
managing discovery reference signals measurement according to an
embodiment of the invention;
[0010] FIGS. 3, 4 and 5 illustrate effective measurement gap
patterns according to some embodiments of the invention;
[0011] FIGS. 6 and 7 illustrate processes for managing discovery
reference signals measurement according to some embodiments of the
invention;
[0012] FIGS. 8 and 9 illustrate blocks diagrams of apparatuses
according to some embodiments of the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0013] The following embodiments are exemplary. Although the
specification may refer to "an", "one", or "some" embodiment(s) in
several locations, this does not necessarily mean that each such
reference is to the same embodiment(s), or that the feature only
applies to a single embodiment. Single features of different
embodiments may also be combined to provide other embodiments.
Furthermore, words "comprising" and "including" should be
understood as not limiting the described embodiments to consist of
only those features that have been mentioned and such embodiments
may contain also features/structures that have not been
specifically mentioned.
[0014] FIG. 1 illustrates a wireless communication scenario to
which embodiments of the invention may be applied. Referring to
FIG. 1, a cellular communication system may comprise a radio access
network comprising base stations disposed to provide radio coverage
in a determined geographical area. The base stations may comprise
macro cell base stations 102 arranged to provide terminal devices
104, 106 with the radio coverage over a relatively large area
spanning even over several square miles, for example. In densely
populated hotspots where improved capacity is required, small area
cell base stations 100 may be deployed to provide terminal devices
104 with high data rate services. Such small area cell base
stations may be called micro cell base stations, pico cell base
stations, or femto cell base stations. The small area cell base
stations typically have significantly smaller coverage area than
the macro base stations 102. The cellular communication system may
operate according to specifications of the 3rd generation
partnership project (3GPP) long term evolution (LTE) advanced or
its evolution version.
[0015] Regarding physical-layer aspects of small cell enhancement,
small cell on/off operation facilitates on/off switching of small
cells e.g. to reduce network energy consumption as well as
interference during the times when the network load is low. This
may require the use of a discovery procedure such as discovery
signals (e.g. discovery reference signals DRS). Cells operating a
cell on/off switching may transmit discovery signal(s) supporting
at least cell identification, coarse time/frequency
synchronization, intra/inter-frequency radio resource management
(RRM) measurement of cells and possibly antenna quasi-co-location
QCL. This includes support of discovery and measurement
enhancement(s) in downlink and its usage in related procedures.
[0016] In a connected mode, measurement gaps allow a terminal
device to tune its receiver to another frequency or another radio
access technology (RAT) to perform measurements. During a
measurement gap, there is no downlink or uplink activity from/in a
serving cell for the terminal device. In LTE system, the
measurement gaps are configured by radio resource control (RRC)
protocol and they occur e.g. with a periodicity of 40 ms or 80 ms
and last e.g. for 6 ms in downlink and 7 ms in uplink. Thus, the
measurement gaps are used in LTE for providing the terminal devices
with possibilities to perform cell search and RRM measurements for
other carriers. During the measurement gap, the terminal device is
not expected to receive data from its serving cell. In order to
avoid the whole cell from becoming unused during the measurement
gaps, the network may configure the measurement gaps of the
terminal devices over time.
[0017] Cell-specific reference signals (CRS) may be transmitted
continuously in every downlink sub-frame. Furthermore, primary and
secondary synchronization signals (PSS/SSS) may occur in every 5th
sub-frame. Therefore, the network is able to configure measurement
gaps flexibly. The network may configure a measurement gap for a
given terminal to occur at any point of time, knowing that the
signals required for RRM measurements (i.e. PSS/SSS/CRS) always
coincide with any 6 ms period.
[0018] Discovery reference signals (DRS) facilitate the discovery
of dormant cells/base station, and/or support transmission point
identification. The discovery reference signals may be used as
reference signals for both cell search and RRM measurements. A DRS
occasion has a duration of one or more sub-frames and comprises
PSS/SSS/CRS and possibly (if configured) channel state information
reference signals (CSI-RS). The DRS occasions are transmitted by
the base station with a periodicity of a few tens or hundreds of
milliseconds. It has been agreed that DRS may only be transmitted
on a downlink sub-frame or DwPTS region of sub-frames. For a
DRS-based measurement, the terminal device assumes that 1) the DRS
occasion for a cell contains one instance of PSS/SSS per Rel-8, 2)
CRS is transmitted at least in the same sub-frame(s) as PSS/SSS, 3)
the DRS occasion may comprise multiple CSI-RS resource element (RE)
configurations, wherein the different CSI-RS configurations may be
in the same or different sub-frame(s), and/or the different CSI-RS
configurations may be scrambled independently, 4) the DRS occasion
may comprise relative sub-frame offset between SSS and one CSI-RS
RE configuration, possibly between variable or fixed within 5 ms
relative to sub-frame of SSS. Further, the terminal device assumes
that the DRS occasion for the cell comprises N consecutive
sub-frames (N<=5). Yet further, the terminal device assumes that
the DRS occasion for the cell is transmitted every M ms, wherein
candidate values for M include 40, 80, 160, and possibly other
values. RAN1 design does not assume any requirements for the number
of detectable cells using DRS.
[0019] It has further been agreed that regarding DRS based
measurements, the terminal device may be configured with one DRS
measurement timing configuration (DMTC) per frequency, wherein the
reference timing for the offset is the primary serving cell's
timing. No new measurement gap pattern is introduced in LTE Rel-12
for DRS-based measurement. For the purpose of DRS based
measurements, the terminal device assumes only the presence of DRS
signals. For both intra- and inter-frequency measurement, if the
terminal device is configured with only DRS-based measurements
reporting on a given carrier frequency, and the terminal device is
not configured with an activated serving cell on that carrier
frequency, the terminal device should not assume the presence of
any signal and channel except for DRS in the DMTC (DRS measurement
timing configuration) duration.
[0020] The relatively large periodicity of DRS transmissions
creates a problem with respect to the measurement gaps. The agreed
measurement gap configuration ("no new measurement gap pattern is
introduced for the DRS-based measurement") and the agreed set of
candidate values for the periodicity of the DRS occasions
("candidate values for M are 40, 80, 160, possibly other values")
may lead into a situation where each of the terminal devices (or at
least a large number of them) perform their DRS-based RRM
measurements at the same times, making it hard for the network to
find terminal devices to be scheduled during the measurement gaps.
This results in a loss of system throughput.
[0021] The terminal device and/or the base station may be allowed
to identify that which of the cells (that the terminal device has
detected and measured) are dormant from the measurement reports
alone.
[0022] The DRS periodicity may be a multiple of 40 ms and align
each measurement gap of each terminal device to match the
occurrence of DRS. However, aligning each measurement gap of each
terminal device creates a window during which no terminal device
measuring the ON/OFF cells can be scheduled, thus reducing the
maximum throughput that the serving cell is able to offer. Further,
the ON/OFF cells need to be synchronised to match the measurement
gap opportunities.
[0023] Modern cellular communication systems are wideband systems
where a large bandwidth may be scheduled to a single terminal
device for the transmission of data. The scheduled resources may be
indicated in terms of physical resource blocks or frequency
resource blocks. Each frequency resource block has a determined
bandwidth and a centre frequency and one or more frequency resource
blocks may be scheduled to the terminal device at a time. The
frequency resource blocks scheduled to the terminal device may be
contiguous and, thus, form a continuous scheduled band for the
terminal device. However, the resource blocks may be non-contiguous
in which case the form a non-contiguous band fragmented into a
plurality of smaller bands.
[0024] Let us now describe an embodiment of the invention for
selecting and signalling measurement gap pattern parameters with
reference to FIG. 2. FIG. 2 illustrates a signalling diagram
illustrating a method for signalling measurement gap pattern
parameters between a base station of a cellular communication
system, e.g. base station 100 or 102, and a terminal device of the
cellular communication system, e.g. the terminal device 104 or 106.
In another embodiment, the procedure of FIG. 2 may be carried out
between the terminal device and an access node or, more generally,
a network node. The network node may be a server computer or a host
computer. For example, the server computer or the host computer may
generate a virtual network through which the host computer
communicates with the terminal device. In general, virtual
networking may involve a process of combining hardware and software
network resources and network functionality into a single,
software-based administrative entity, a virtual network. Network
virtualization may involve platform virtualization, often combined
with resource virtualization. Network virtualization may be
categorized as external virtual networking which combines many
networks, or parts of networks, into the server computer or the
host computer. External network virtualization is targeted to
optimized network sharing. Another category is internal virtual
networking which provides network-like functionality to the
software containers on a single system. Virtual networking may also
be used for testing the terminal device.
[0025] Referring to FIG. 2, a communication link is established
between the base station and the terminal device (step 200). Step
200 may comprise establishment of a control channel connection. The
control channel connection may comprise a radio resource control
(RRC) connection. In block 201, the base station determines, at
least one measurement gap pattern for the terminal device. In block
202, the base station determines, for the terminal device, a DRS
measurement timing configuration for measuring discovery reference
signals. In block 203, the base station determines, for the
terminal device, an effective measurement gap pattern (EMGP), based
on the measurement gap pattern and the DRS measurement timing
configuration. The order in which DMTC and MGP are configured is
not relevant, either may be configured first. MGP may be configured
first, but just as well the terminal device may be first configured
for the DRS measurements, and after that MGP may be decided based
on what the resulting EMGP may look like. In block 204, the base
station determines whether there are unused (i.e. free/available)
measurement gaps that are usable for normal scheduling of
PUSCH/PDSCH/PDCCH/PUCCH data. In step 205, the base station
transmits a control message to the terminal device. The control
message comprises at least one information element indicating an
RRC configuration for the terminal device, comprising the
measurement gap pattern and the DRS measurement timing
configuration. The terminal device acquires the control message
from the base station in step 205 and stores the information on the
measurement gap pattern and the DRS measurement timing
configuration. MGP and DMTC may also be transmitted independently
of each other. For example, the terminal device may have MGP for
other purposes, and the base station may then decide to activate
DMTC. The information may be used in connection with transferring
data with the base station, as described next. In block 206, the
terminal device determines an implicit or an explicit effective
measurement gap pattern based on the at least one measurement gap
pattern and the DRS measurement timing configuration. In block 207,
the terminal device determines whether there are unused measurement
gaps, and, if there are, the terminal device uses (block 208) those
for one or more of PDCCH monitoring, PUCCH transmission, PUSCH
transmission, and PDSCH reception.
[0026] Small cell ON/OFF switching and related discovery procedures
are hereby enhanced by defining how discovery reference symbols
(DRS) work together with existing measurement gaps. It is defined
how the terminal device measures the ON/OFF cells operating on
inter-frequencies, and it is ensured that each terminal device in
the cell does not perform the inter-frequency measurement at the
same time. The network is thus able to determine and reuse some
gaps assigned to the terminal device. The network is able to
configure measurement gaps at different times for different
terminals, allowing better scheduling efficiency. A different DRS
timing is also allowed for different cells on a frequency, or
different cells in different frequencies.
[0027] In an embodiment, the terminal device performs, at time
instances defined in the effective measurement gap pattern, at
least one of intra- and inter-frequency measurements.
[0028] In an embodiment, the terminal device determines
carrier-specific effective measurement gap patterns based on the
measurement gaps and the DRS measurement timing configuration such
that only those measurement gaps that coincide with the DRS
measurement timing configuration of the carrier are included into
the carrier-specific effective measurement gap patterns.
[0029] In an embodiment, the terminal device determines, based on
the carrier-specific effective measurement gap patterns, a combined
effective measurement gap pattern indicating which measurement gaps
are used in any of measured carriers.
[0030] In an embodiment, the terminal device determines, based on
the measurement gaps and the combined effective measurement gap
pattern, which measurement gaps are not needed, and utilizes those
measurement gaps for reception and/or transmission.
[0031] In an embodiment, the terminal device monitors its serving
cell during the measurement gaps that are not needed.
[0032] In an embodiment, the terminal device determines EMGP based
on the measurement gap pattern and an explicit indication of a DRS
occasion transmission configuration.
[0033] In an embodiment, the terminal may perform inter-frequency
measurements on a given carrier only when EMGP indicates so, i.e.
when the measurement gap pattern and the measurement occasion
pattern overlap. To allow the network to configure different
terminal devices with different patterns, periodicities of the
measurement gap pattern and the measurement occasion pattern are
supposed not to be multiples of each other.
[0034] In an embodiment, the indication of EMGP may be implicit or
explicit. An implicit indication may be accomplished by e.g. a
fixed value (e.g. 30 or 50 ms) for DMTC or by the terminal device
calculating EMGP based on a signalled DRS periodicity value. An
explicit indication may be accomplished by e.g. explicitly
indicating the DMTC pattern to be used or by indicating the unused
gaps explicitly.
[0035] In an embodiment, EMGP is applied only to intra-frequency
measurements, only to inter-frequency measurements, or to both
types of measurements.
[0036] In an embodiment, measurement gaps (only) apply to
inter-frequency measurements for ON/OFF cells with EMGP. In an
embodiment, measurement gaps also apply to intra-frequency
measurements in order to guarantee that the terminal device is
grabbing at least as many samples for intra-frequency measurements
of ON/OFF-cells as for inter-frequency measurements and that the
terminal device does not look around without being able to measure
anything due to DRS not being transmitted.
[0037] In an embodiment, s-measure (i.e. the terminal device not
being allowed to perform measurements when the measured quality of
the serving cell is good over an indicated threshold) may not apply
to ON/OFF cells measured with EMGP. This means that indicating EMGP
also indicates disregarding the s-measure for the DRS measurements.
Alternatively, a separate s-measure may be signalled for the ON/OFF
measurements during EMGP but even in this case the normal s-measure
may not apply for the ON/OFF-cells.
[0038] In an embodiment, L1/L3 filtering of measurements for ON/OFF
cells measured with EMGP may be different from normal RRM
measurements, i.e. the indication of EMGP also indicates the used
L1/L3 filtering (implicitly or explicitly).
[0039] In an embodiment, EMGP is cell-specific within a carrier,
indicating that some cells may only be measured at some EMGP
occasions. This allows the network more freedom when configuring
the DRS transmission occasions for different cells, e.g. for
interference coordination purposes.
[0040] In an embodiment, with EMGP the ON/OFF cells are configured
with a DRS periodicity that is not the periodicity of the terminal
device measurement gaps in order to introduce effective measurement
gaps that coincide with DRS. I.e. to guarantee that even without
synchronisation, DRS and the measurement gap coincide after a fixed
number of measurement gap occurrences. For instance, with a DRS
periodicity of 30 ms and a measurement gap periodicity of 40 ms,
DRS coincides with the measurement gap every 120 ms. For a single
terminal device, this may be accomplished e.g. with a DMTC
periodicity of 30 ms as illustrated in FIG. 3.
[0041] FIG. 3 illustrates the effective measurement gap pattern
EMGP from a single terminal device's perspective, highlighting how
DMTC and measurement gaps create the EMGP pattern (EMGP--UE
perspective: DRS/DMTC periodicity=30 ms, gap pattern=40 ms).
[0042] FIG. 4 illustrates the network perspective, showing how
network may configure different terminal devices with different
measurement gap starting occasions despite of the same DRS
configuration in the carrier (EMGP--network perspective (DRS/DMTC
periodicity=30 ms, gap pattern=40 ms).
[0043] FIG. 5 illustrates how EMGP may end up being the same as a
legacy gap pattern but with different gaps used for different
carriers/cells (combined EMGP for a single UE:
cell/carrier-specific DMTC configuration).
[0044] Let us now describe some embodiments with reference to FIGS.
6 and 7.
[0045] Referring to FIG. 6, the base station may establish a
communication link with the terminal device (step 600). Step 600
may comprise establishment of a control channel connection. The
control channel connection may comprise a radio resource control
(RRC) connection. In block 601, the base station determines, at
least one measurement gap pattern for the terminal device. In block
602, the base station determines, for the terminal device, a DRS
measurement timing configuration for measuring discovery reference
signals. In block 603, the base station determines for the terminal
device, based on the measurement gap pattern and the DRS
measurement timing configuration for measuring discovery reference
signals, an effective measurement gap pattern (EMGP). In block 604,
the base station determines whether there are unused (i.e.
free/available, not used for DRS measurements) measurement gaps
that are usable for normal scheduling of PUSCH/PDSCH/PDCCH/PUCCH
data. In block 605, the base station transmits a control message to
the terminal device. The control message comprises at least one
information element indicating an RRC configuration for the
terminal device, comprising the measurement gap pattern and the DRS
measurement timing configuration. If there are unused measurement
gaps, they may be used (block 606) for one or more of PDCCH
monitoring, PDCCH transmission, PDSCH transmission, and PUSCH
reception.
[0046] Referring to FIG. 7, the terminal device may establish a
communication link with the base station (step 700). Step 700 may
comprise establishment of a control channel connection. The control
channel connection may comprise a radio resource control (RRC)
connection. In block 701, the terminal device acquires a control
message from the base station. The control message comprises at
least one information element indicating an RRC configuration for
the terminal device, comprising the measurement gap pattern and the
DRS measurement timing configuration. The terminal device may store
the information on the measurement gap pattern and the DRS
measurement timing configuration. The information may be used in
connection with transferring data with the base station, as
described next. In block 702, the terminal device determines an
implicit or an explicit effective measurement gap pattern based on
the at least one measurement gap pattern and the DRS measurement
timing configuration. In block 703, the terminal device determines
whether there are unused measurement gaps, and, if there are, the
terminal device uses (block 704) those for one or more of PDCCH
monitoring, PUCCH transmission, PUSCH transmission, and PDSCH
reception.
[0047] In an embodiment, the embodiments of FIGS. 6 and 7 may be
combined. In a modification, the processes of FIGS. 6 and/or 7 may
be exclusive to small area cell base stations, e.g. the base
station 100 may carry out the embodiments of FIG. 2, 6, and/or 7
but the macro base station 102 may not.
[0048] An embodiment provides an apparatus comprising at least one
processor and at least one memory including a computer program
code, wherein the at least one memory and the computer program code
are configured, with the at least one processor, to cause the
apparatus to carry out the procedures of the above-described base
station or the network node. The at least one processor, the at
least one memory, and the computer program code may thus be
considered as an embodiment of means for executing the
above-described procedures of the base station or the network node.
FIG. 8 illustrates a block diagram of a structure of such an
apparatus. The apparatus may be comprised in the base station or
the network node, e.g. the apparatus may form a chipset or a
circuitry in the base station or the network node. In some
embodiments, the apparatus is the base station or the network node.
The apparatus comprises a processing circuitry 10 comprising the at
least one processor. The processing circuitry 10 may comprise an
MGP determination circuitry 16 configured to determine, at least
one measurement gap pattern for the terminal device. A DMTC
determination circuitry 18 may be configured to determine for the
terminal device a DRS measurement timing configuration for
measuring discovery reference signals. An EMGP determination
circuitry 19 may be configured to determine, for the terminal
device, an effective measurement gap pattern (EMGP) based on the
measurement gap pattern and the DRS measurement timing
configuration for measuring discovery reference signals. Upon
determining the DRS measurement timing configuration, the DMTC
determination circuitry 19 may output a signal indicating the
determined DMTC and MGP to a control message generator 12
configured to generate the control message indicating the
determined DMTC and MGP to the terminal device for which DMTC and
MGP are determined.
[0049] The apparatus may further comprise a scheduler circuitry 14
configured to schedule frequency resource blocks in transmission
time intervals to the terminal devices. The scheduler circuitry 14
may output to the control message generator information on the
schedulings and the control message generator 12 may create the
scheduling messages indicating the schedulings to the terminal
devices on a control channel.
[0050] The processing circuitry 10 may comprise the circuitries 12
to 19 as sub-circuitries, or they may be considered as computer
program modules executed by the same physical processing circuitry.
The memory 20 may store one or more computer program products 24
comprising program instructions that specify the operation of the
circuitries 12 to 19. The memory 20 may further store a database
comprising definitions for the selection of the link adaptation
scheme, for example. The apparatus may further comprise a
communication interface 22 providing the apparatus with radio
communication capability with the terminal devices. The
communication interface 22 may comprise a radio communication
circuitry enabling wireless communications and comprise a radio
frequency signal processing circuitry and a baseband signal
processing circuitry. The baseband signal processing circuitry may
be configured to carry out the functions of the transmitter and/or
the receiver, as described above in connection with FIGS. 1 to 7.
In some embodiments, the communication interface may be connected
to a remote radio head comprising at least an antenna and, in some
embodiments, radio frequency signal processing in a remote location
with respect to the base station. In such embodiments, the
communication interface 22 may carry out only some of radio
frequency signal processing or no radio frequency signal processing
at all. The connection between the communication interface 22 and
the remote radio head may be an analogue connection or a digital
connection.
[0051] An embodiment provides another apparatus comprising at least
one processor and at least one memory including a computer program
code, wherein the at least one memory and the computer program code
are configured, with the at least one processor, to cause the
apparatus to carry out the procedures of the above-described
terminal device. The at least one processor, the at least one
memory, and the computer program code may thus be considered as an
embodiment of means for executing the above-described procedures of
the terminal device. FIG. 9 illustrates a block diagram of a
structure of such an apparatus. The apparatus may be comprised in
the terminal device, e.g. it may form a chipset or a circuitry in
the terminal device. In some embodiments, the apparatus is the
terminal device. The apparatus comprises a processing circuitry 50
comprising the at least one processor. The processing circuitry 50
may comprise a communication controller circuitry 54 configured to
extract control messages received from a serving base station, to
acquire the measurement gap pattern and the DRS measurement timing
configuration determined for the terminal device, and to control
the terminal device to transmit or receive data between the base
station in the scheduled communication resources. The apparatus may
further comprise an EMGP determination circuitry 52 configured to
determine an implicit or an explicit effective measurement gap
pattern based on the at least one measurement gap pattern and the
DRS measurement timing configuration.
[0052] The processing circuitry 50 may comprise the circuitries 52,
54 as sub-circuitries, or they may be considered as computer
program modules executed by the same physical processing circuitry.
The memory 60 may store one or more computer program products 64
comprising program instructions that specify the operation of the
circuitries 52, 54. The apparatus may further comprise a
communication interface 62 providing the apparatus with radio
communication capability with base stations of one or more cellular
communication networks. The communication interface 62 may comprise
a radio communication circuitry enabling wireless communications
and comprise a radio frequency signal processing circuitry and a
baseband signal processing circuitry. The baseband signal
processing circuitry may be configured to carry out the functions
of the transmitter and/or the receiver, as described above in
connection with FIGS. 1 to 8.
[0053] As used in this application, the term `circuitry` refers to
all of the following: (a) hardware-only circuit implementations
such as implementations in only analog and/or digital circuitry;
(b) combinations of circuits and software and/or firmware, such as
(as applicable): (i) a combination of processor(s) or processor
cores; or (ii) portions of processor(s)/software including digital
signal processor(s), software, and at least one memory that work
together to cause an apparatus to perform specific functions; and
(c) circuits, such as a microprocessor(s) or a portion of a
microprocessor(s), that require software or firmware for operation,
even if the software or firmware is not physically present.
[0054] This definition of `circuitry` applies to all uses of this
term in this application. As a further example, as used in this
application, the term "circuitry" would also cover an
implementation of merely a processor (or multiple processors) or
portion of a processor, e.g. one core of a multi-core processor,
and its (or their) accompanying software and/or firmware. The term
"circuitry" would also cover, for example and if applicable to the
particular element, a baseband integrated circuit, an
application-specific integrated circuit (ASIC), and/or a
field-programmable grid array (FPGA) circuit for the apparatus
according to an embodiment of the invention.
[0055] The processes or methods described above in connection with
FIGS. 1 to 9 may also be carried out in the form of one or more
computer process defined by one or more computer programs. The
computer program shall be considered to encompass also a module of
a computer programs, e.g. the above-described processes may be
carried out as a program module of a larger algorithm or a computer
process. The computer program(s) may be in source code form, object
code form, or in some intermediate form, and it may be stored in a
carrier, which may be any entity or device capable of carrying the
program. Such carriers include transitory and/or non-transitory
computer media, e.g. a record medium, computer memory, read-only
memory, electrical carrier signal, telecommunications signal, and
software distribution package. Depending on the processing power
needed, the computer program may be executed in a single electronic
digital processing unit or it may be distributed amongst a number
of processing units.
[0056] The present invention is applicable to cellular or mobile
communication systems defined above but also to other suitable
communication systems. The protocols used, the specifications of
cellular communication systems, their network elements, and
terminal devices develop rapidly. Such development may require
extra changes to the described embodiments. Therefore, all words
and expressions should be interpreted broadly and they are intended
to illustrate, not to restrict, the embodiment. It will be obvious
to a person skilled in the art that, as technology advances, the
inventive concept can be implemented in various ways. The invention
and its embodiments are not limited to the examples described above
but may vary within the scope of the claims.
LIST OF ABBREVIATIONS
[0057] 3GPP third generation partnership program
[0058] CRS cell-specific reference signals
[0059] CSI-RS channel state information reference signal
[0060] DCI downlink control information
[0061] DL downlink
[0062] DMTC DRS measurement timing configuration
[0063] DRS discovery reference signals
[0064] EMGP effective measurement gap pattern
[0065] eNB base station
[0066] LTE long term evolution
[0067] MBSFN multimedia broadcast multicast service single
frequency network
[0068] PSS primary synchronisation signal
[0069] RAN radio access network
[0070] RAT radio access technology
[0071] Rel release
[0072] RRM radio resource management
[0073] SSS secondary synchronisation signal
[0074] UE user equipment
* * * * *